Zeljko Djurisic

Optimal Reactive Compensators in Power Systems Under Asymmetrical and Nonsinusoidal Conditions

Based on the condition for the minimum rms value of line currents, a method for improving the power factor in power systems under asymmetrical and nonsinusoidal conditions is presented. This paper offers straightforward and convenient formulations of active currents for the three-phase four-wire, three-phase three-wire, and single-phase systems. Owing to the transformation matrix introduced in this paper, the formulation of active currents is valid regardless of whether the voltages and currents are balanced or unbalanced and it permits any point of the system to be chosen for the voltage reference. Observing the constraints related to the reactive compensators, the line current minimization procedure is used for the determination of optimal compensating capacitances for the three-phase four-wire, three-phase three-wire, and single-phase systems. The optimal reactive compensators based on up to six capacitors are proposed. The definitions of power factors before and after compensation are introduced. The influence analysis of nonactive power compensation on harmonic distortion of line currents has been also performed. Experimental results are obtained to confirm the validity and applicability of the proposed compensation procedure.

Vertical wind speed profiles estimation recognizing atmospheric stability

This thesis represents the analysis of the atmospheric stability influence on wind speed profile. The comparison of the results obtained from this simulation and ones obtanied using clasic logaritmic law wich does not take in account stability conditions, has been done.

Current carrying capacity of overhead line that connects wind power plant to the grid

The mathematical model for calculating conductor temperature of overhead transmission line (OHTL) has been developed in this paper. This model is able to calculate conductor temperature for real meteorological conditions. Also it can be used for calculating temperature in case that electrical current which flows through conductor is produced using wind turbines. Using this model the critical conditions for calculating current-carrying capacity of transmission line that connects wind power plant to the grid can be determined. The importance of this study is to show that the overhead lines that connect wind turbines on the grid can be significantly overloaded, comparing to the values that are given by current standards and technical reports. This is possible due to better cooling conditions of conductors. During the production of electrical energy in wind turbine, it is assumed that the wind speed that is used for energy production is also used for conductor cooling.

Fuzzy based computational efficiency for optimal wind farm layout design

This paper deals with the topic of optimal wind farm layout design on complex terrains. The paper proposes optimization model that reflects the actual requirements of realistic wind farms. Fuzzy based computational efficiency model is proposed. Computational efficiency model takes account of environmental impact of a wind farm, land costs, costs of auxiliary roads, installation and maintenance costs, costs of electrical infrastructure, etc. Fuzzy logic deals with uncertainties that can occur while quantifying computational efficiency. Using genetic algorithm, the proposed model has been tested on a realistic wind farm terrain in Serbia.

10.5937/zeint24-4934 = Analysis of technical-economic requirements for the construction of a solar power plant on the roof of the business building of the Electrical Engineering Institute 'Nikola Tesla'

У раду је приказана анализа техно-економских услова изградње соларне електране на крову пословне зграде Електротехничког института „Никола Теслаˮ у Београду. Извршен је прорачун ирадијације која пада на соларне панеле постављене на датој локацији у току ведрог дана, као и прорачун који је заснован на резултатима мерења хоризонталне ирадијације у Београду. Приказано је идејно решење распореда панела на крову зграде и њиховог повезивања на инверторе. Проверени су услови за прикључење електране на дистрибутивну мрежу и извршена је економска анализа пројекта.